Submarine connection assembly

Abstract

A submarine connection for interconnecting a riser pipe and a flexible pipe (26). The riser pipe has an upper end and the flexible pipe (26) has a lower end (30). A connection assembly includes a rigid fitting having a first limb (64) to be connected to the lower end (30) and a second limb (66) with a connector (67) on the end, and a body (36) having a head (42) and an opposing base (46) provided with an end piece (52) to be mounted on the upper end. The connection assembly also includes first guiding elements (60, 86) secured to the body (36), extending in a position at a distance from the axis of the end piece (52), and second guiding elements (76, 81) secured to the first limb (64), suitable for cooperating with the first guiding elements (60, 86).

Claims

1. An underwater connection assembly for connecting, between a seabed and a sea surface, a riser extending from the seabed with a flexible pipe leading to the surface, the connection assembly comprising: the riser having an upper end, the flexible pipe having a lower end; a rigid U shaped coupling having a first limb connectable to the lower end and an opposite second limb ending in a connector; a frame having a top configured to be connected to a float and an opposite bottom; an end piece on the bottom and having an axis oriented toward the top end for being mounted on the upper end; a guide device configured to allow the connector to be guided in movement toward the end piece so that the connector and the end piece can be coupled together; the guide device comprising first guide members secured to frame, and second guide members secured to the U shaped coupling and the second guide members are able to collaborate with the first guide members, and the first and second guide members further comprise a damper configured to damp the movement of the connector toward the end piece.

2. The underwater connection assembly as claimed in claim 1, further comprising, the first guide members extending in a position that is away from an axis of the end piece, while the second guide members are secured to the first limb of the coupling.

3. The underwater connection assembly as claimed in claim 1 further comprising: a guide beam mounted transversely of the first limb of the coupling and extending in a direction of the second limb of the coupling; and the second guide members are installed on the guide beam.

4. The underwater connection assembly as claimed in claim 3, further comprising: an extension of the guide beam extending away from the second limb of the coupling so that the rigid coupling can be suspended.

5. The underwater connection assembly as claimed in claim 1, further comprising: the second guide members comprising a telescopic sleeve oriented substantially parallel to the second limb to form the damper.

6. The underwater connection assembly as claimed in claim 5, further comprising: the telescopic sleeve having a first element defining a cylindrical chamber, and a second element defining a piston closing the cylindrical chamber and allowing a gas to be trapped inside the cylindrical chamber under the piston.

7. The underwater connection assembly as claimed in claim 1, further comprising: the first guide members comprising a tubular receptacle oriented substantially parallel to an axis of the end piece.

8. The underwater connection assembly as claimed in claim 5, further comprising: the telescopic sleeve and a tubular receptacle having cooperating indexing members configured for guiding the telescopic sleeve and the tubular receptacle in rotation relative to one another.

9. The underwater connection assembly as claimed in claim 8, wherein the indexing members comprise the telescopic sleeve having a radially projecting indexing piece and the tubular receptacle having a cooperating axial slot to together form the indexing members.

10. The underwater connection assembly as claimed in claim 1, further comprising: the frame comprising two uprights that are substantially parallel and spaced apart and two supports that are secured respectively to the uprights, and the first guide members are mounted on the supports.

Description

(1) Other specifics and advantages of the invention will become apparent from reading the description given hereinafter of one particular embodiment of the invention, given by way of nonlimiting indication, with reference to the attached drawings in which:

(2) FIG. 1 is a schematic view of the implementation of an underwater connection assembly according to the invention;

(3) FIG. 2 is a schematic side view of the connection assembly according to the invention in a first phase of implementation;

(4) FIG. 3A is a schematic detailed view of the connection assembly depicted in, FIG. 2 in a second phase of implementation;

(5) FIG. 3B is a schematic plan view in section on IIIB-IIIB illustrated in FIG. 3A;

(6) FIG. 4 is a schematic detailed view of the connection assembly depicted in FIG. 2, in a third phase of implementation; and

(7) FIG. 5 is a schematic perspective view of the connection assembly illustrated in FIG. 2 in the said third phase of implementation.

DESCRIPTION OF AN EMBODIMENT

(8) FIG. 1 schematically depicts a tower 10 comprising a rigid riser 12 fixed to a seabed 14 by means of an anchoring system 16. Furthermore, the rigid pipe 12 has an upper part 18 suspended from a float 20 in which there is trapped a sufficient quantity of air to keep the rigid pipe in a vertical position. The float 20 is situated in a zone comprised between the seabed 14 and a surface 22, more specifically near the surface 22. This zone is nevertheless chosen to be some distance away from the surface 22, for example 30 m away, approximately, so as to be less dependent on surface movements.

(9) FIG. 1 also illustrates a pipe-laying vessel 24 sailing on the surface 22 vertically above the tower 10. A flexible pipe 26 is suspended from the pipe-laying vessel 24 via a cable 28. The flexible pipe 26 has a lower end 30 extended by a rigid U-shaped coupling 32 which ends in a connector 34. These elements secured to the flexible pipe 26 will be described in greater detail hereinafter. This flexible pipe is borne by the pipe-laying vessel 24 in the vicinity of the upper part 18 of the rigid pipe 12 so as to be connected thereto as will be explained later. To do that, the upper part 18 of the rigid pipe 12 comprises a longitudinal frame 36 that will be described first of all in three-quarter view and with reference to FIG. 5.

(10) FIG. 5 again shows the frame 36. It has two parallel cylindrical main uprights 38, 40 of a length of, for example, between 10 and 15 m. The main uprights 38, 40 are joined together in an upper end 42 of the frame 36 forming the top, by an upper crossmember 44 connected to the float 20, not depicted here, and in a lower end 46 forming the bottom, by a lower crossmember 48. FIG. 5 again shows the upper part 18 of the rigid riser which ends in a connection upper end 52 forming an end piece, and is held in engagement through the lower crossmember 48 between the main uprights 38, 40, substantially equidistant therefrom.

(11) Furthermore, the frame 36 is equipped with two parallel supports 56, 54 respectively secured to the said uprights. The two supports 56, 54 being connected to one another by a supporting crossmember 58 so as to form a bracket. The frame 36 is then equipped with first guide members 60 installed on the supporting crossmember 58, separated from the connection upper end 52 and that will be described in greater detail in FIG. 2.

(12) FIG. 2 illustrates the situation in which, by action of the pipe-laying vessel 24 depicted in FIG. 1, the flexible pipe 26 equipped with its rigid U shaped coupling 32 has been brought level with the frame 36. All the elements present will be described in detail first of all before tackling how they interact.

(13) FIG. 2 thus again shows the frame 36 in side view and the connection upper end 52 which ends in a male tailpiece 62. The tailpiece and the connection upper end 52 are coaxial and their common axis extends towards the upper end 42 of the frame 36. Also visible are the supports 54, 56 and the first guide members 60 formed of a tubular receptacle oriented substantially parallel to and some distance away from the connection upper end 52. It will also be seen that the tubular receptacle 60 is in a position spaced away from the parallel cylindrical uprights 38, 40.

(14) FIG. 2 once again also shows the lower end 30 of the flexible pipe 26, equipped with the rigid U-shaped coupling 32. The latter has a first limb 64 and an opposite second limb 66. The latter ends in a connector 67. The two limbs 64, 66 are inclined relative to one another for example by an angle of between 30 and 20. The first limb 64 has a reinforced portion 68 directly connected to the lower end 30. This reinforced portion 68 passes through a guide beam 70 to which it is secured. The reinforced portion 68 is kept inclined with respect to the guide beam 70 by an angle of close to 90 minus the angle of inclination of the two limbs 64, 66 relative to one another.

(15) The guide beam 70 has an internal part 72 oriented towards the second limb 66 and the connector 67 and away from the reinforced portion 68, an extension 74 forming an external part, at the end of which the cable 28 is tethered.

(16) In addition, the internal part 72 is equipped with a telescopic sleeve 76 forming the second guide members. The telescopic sleeve 76 extends substantially perpendicular to the guide beam 70 and in a direction substantially parallel to the second limb 66. It will be seen that the telescopic sleeve 76 extends in an opposite direction to the curved inside of the rigid coupling 32. Furthermore, the telescopic sleeve 76 is circular in cross section and has a first element 78 secured to the guide beam 70 and forming a cylindrical chamber 79. It also has a second element 80 forming a piston mounted with the ability to move translationally inside the first element 78. Also, the second element 80 has a free end 77 which extends as a projection from the first element 78 and, on the opposite side, a reinforced end 83 equipped with a seal intended to seal the cylindrical chamber 79 closed. The second element 80 forming the piston allows a gas to be trapped fluid-tightly inside the cylindrical chamber. The gas, for example nitrogen, is elastically compressible and will therefore be able to act as a damper as will be explained hereinafter.

(17) In addition, the first element 78 of the sleeve 76 is provided with an indexing piece 81.

(18) The tubular receptacle 60 has an end wall 82 and an opposite chamfered or frustoconical opening 84. Furthermore, it has a diameter identical to the diameter of the sleeve 76, to within a functional clearance. A longitudinal slot 86 is formed axially in the wall of the tubular receptacle 60 so as to be able to accept the indexing piece 81.

(19) FIG. 3A shows again in detail the telescopic sleeve 76 secured to the internal part 72 of the guide beam 70 and, more specifically shows the first element 78 of the sleeve 76, forming a cylindrical chamber 79, in which the second element 80 that forms a piston is slidingly engaged. It also again shows the tubular receptacle 60 with its chamfered opening 84, inside which the free end 77 of the second element 80 of the sleeve 76 is partially engaged. FIG. 3B again shows, viewed from above, the tubular receptacle 60 with its longitudinal slot 86 and the second element 80 of the sleeve 76.

(20) In FIG. 2, it may be seen that the center-distance between the sleeve 76 and the second limb 66, namely the distance between their axes, in a perpendicular direction, is equal to the center-distance between the connection upper end 52 and the tubular receptacle 60.

(21) Furthermore, the indexing piece 81 and the slot 86 (FIG. 3B) are respectively engineered so that when they are engaged one inside the other, the second limb 66 equipped with the connector 67 and the connection upper end 52 are coaxial.

(22) Thus, in FIG. 2, the cable 28 has been guided so as to be able to bring the rigid U shaped coupling 32 closer to the frame 36 and so as to bring the second limb 66 between the uprights 38, 40, while the sleeve 76 is brought to face the chamfered opening 84 of the tubular receptacle 60.

(23) It will also be seen that the guide beam 70 suspended from the cable 28 by the extension 74 thereof runs substantially horizontally thanks to the weight of the flexible pipe 26. Hence, the connection upper end 52 and the frame 36 are kept vertical thanks to the tension applied by the float 20, which is held by the pipe 12.

(24) From the situation as depicted in FIG. 2, the cable 28 is relaxed further, so that the second element 80 of the sleeve 76 approaches the chamfered opening 84 of the tubular receptacle 60. The chamfered opening 84 thus forms a ramp for the second element 80 so as to guide it toward the center of the tubular receptacle 60. Thus, as the sleeve 76 descends, thanks to the chamfered opening 84, despite the lateral movements of the sleeve 76 which are caused mainly by the movements of the pipe-laying vessel 24 it nevertheless enters the tubular receptacle 60.

(25) Furthermore, as illustrated by FIG. 3A, the angular orientation of the sleeve 76 is controlled by the engagement of the indexing piece 81 in the slot 86. Hence, when the cable 28 is relaxed further still, the sleeve 76 fits into the tubular receptacle 60 and, more specifically, the free end 77 of the second element 80 comes to bear against the end wall 82, and under the weight of the guide beam 70 supporting the flexible pipe 26, the second element 80 has a tendency to enter the first element 78, at the same time compressing the gas situated inside the cylindrical chamber 79. In that way, the movement of the rigid coupling 32 toward the frame 36 is slowed and braked, so that the connector 67 approaches the tailpiece 62 at a speed that allows the connection to be made without a jolt.

(26) FIG. 4 illustrates just such a situation. In this way, the first element 78 is wedged radially between the second element 80 and the internal wall of the tubular receptacle 60. Thus, the sleeve 76 is locked inside the tubular receptacle 60.

(27) Thanks to the indexing and, more specifically, to the use of the indexing piece 81 inside the slot 86, the connector 67 has, in parallel, come to fit over the male tailpiece 62 of the connection upper end 52 in order to lock automatically thereto.

(28) FIG. 5 again shows the connector 67 connected to the connection upper end 52 on the male tailpiece 62 which it hides in the figure. Thus, the flexible pipe 26 and the riser 12 are connected to one another so that a hydrocarbon can be transported.